create-icon-handle

Arguments:
pixmap

Returns an icon handle, which can be used as the icon of a window's titlebar, or as
the pixmap-icon
property of controls that display pixmaps or passed to copy-to-stream or copy-pixels-to-stream. The pixmap
object should contain a mask in addition to the usual texture.

An icon handle is like a pixmap handle (a handle to a device-dependent
pixmap that resides in the OS) that has a mask built in, so that the
background color or whatever was drawn before the icon can show
through the icon.

See also extract-icon-from-file, for
creating icons from Windows icon files rather than from Common
Graphics pixmaps.